Stimulation of human T cell colony growth by a lymphocyte colony enhancement factor derived from lymphocyte subpopulations

Blood mononuclear cells (MNC) develop into T cell colonies when the cells are sensitized with PHA and seeded in a two-layer soft agar system. Conditioned medium (CM) derived from MNC enhanced lymphocyte colony formation when it was added to the culture system. CFU-TL appear to be stimulated into colony formation by molecules secreted by lymphocyte subpopulations contained in the seeded cells. In this study, human peripheral blood MNC were fractionated by a battery of techniques into adherent, E+, CD4+, CD8+, B and null cells. CM was prepared from each of the subpopulations and its effects on T cell colony growth assayed. All the lymphocyte subpopulations were found to generate lymphocyte colony enhancement factor (LCEF). After several purification procedures, CM prepared from CD4 and CD8+, displayed LCEF activity corresponding to proteins of molecular weight 30-40 and 100-140 kD.     

The influence of T lymphocyte subsets and humoral factors on colony formation by human bone marrow and blood megakaryocyte progenitor cells in vitro

Cellular and humoral influences of T lymphocytes on human megakaryocyte colony formation in vitro were assessed by using a microagar system. Megakaryocyte colony formation from nonadherent low density T lymphocyte-depleted (NALDT-) bone marrow cells was increased significantly after the addition of aplastic anemia serum (AAS) or purified megakaryocyte colony-stimulating factor (Meg-CSF). The addition of conditioned medium obtained from phytohemagglutinin-stimulated T lymphocytes replaced, at least partially, the requirement for AAS or purified Meg-CSF for the growth of megakaryocyte colonies. The cellular influence of T lymphocytes and T lymphocyte subsets on megakaryocyte colony formation was assessed by removing either T cells from nonadherent peripheral blood mononuclear cells with monoclonal OKT4, OKT8, or OKT3 antibodies plus complement, or by adding back populations of bone marrow or blood T4+ or T8+ lymphocytes, isolated by means of fluorescence-activated cell sorting, respectively, to NALDT--bone marrow or -blood cells. When sorted T cell subpopulations were added to a fixed number of NALDT--bone marrow or -peripheral blood cells in the presence of AAS or Meg-CSF, T4+ cells enhanced megakaryocyte colony formation and T8+ cells decreased it. These studies demonstrate that although the stimulation of megakaryocytic progenitor cells by Meg-CSF may not require the presence of monocytes or T lymphocytes, T4+ lymphocytes enhance and T8+ lymphocytes down-regulate megakaryocyte colony formation induced by Meg-CSF. These observations suggest that the immune system is capable of modulating the proliferative response of human megakaryocytic progenitor cells to Meg-CSF.     

The role of interleukin 1 and interleukin 2 in human T colony formation

We investigated the roles of interleukin 1 (IL1) and interleukin 2 (IL2) on T colony formation by PHA-stimulated peripheral blood lymphocytes (PBL). Purified T cells stimulated by PHA could not generate T colonies as did PBL. Media conditioned by PHA-stimulated PBL (PHA-LCM) contained IL2 and a T colony-promoting activity (TCPA) which induced T colony formation in PHA-stimulated purified T cells. IL2 and TCPA are coeluted in the same peak of 18,000 molecular weight after gel filtration chromatography. Moreover, TCPA present in the PHA-LCM could be absorbed on IL2-sensitive cells which possessed specific receptors for IL2. These results suggest that TCPA and IL2 are related entities. Monocytes or IL1 (a monokine released by activated monocytes) also induced T colony formation in purified T cells. Phorbol myristate acetate (PMA) could replace monocytes in the induction of T colony. Monocytes, IL1, or PMA are known to be crucial requirements for IL2 production by PHA-stimulated T cells. This combined with the fact that IL2 participates in T colony formation suggests that monocytes induce T colony formation through IL2 production.     

Granulocyte-macrophage colony formation in serum-free culture: effects of purified colony-stimulating factors and modulation by hydrocortisone

The effects of three purified colony-stimulating factors (CSFs) with different specificities for the granulocyte (G) and macrophage (M) lineages (G-CSF, CSF-1 and GM-CSF) were studied in a serum-free clonal assay system. The results were compared with those obtained in similar cultures containing fetal calf serum (FCS). Total clone (greater than or equal to 10 cells) and colony (greater than or equal to 50 cells) numbers were enhanced by FCS under most conditions. However, the extent of enhancement was highly dependent on the concentration and type of CSF. In some instances, FCS also altered the proportions of G, M, and mixed GM clones induced by the CSFs. In cultures stimulated with GM-CSF, enhancement by FCS was significant only at low CSF concentrations, primarily due to increased numbers of M clones. In contrast, clonal growth was increased by FCS only at high concentrations of CSF-1. Clone and colony numbers induced by G-CSF were greatly increased in cultures with FCS at all CSF concentrations tested. Virtually all clones developing in serum-free medium with G-CSF were pure G, whereas, M and GM clones were usually present in serum-containing cultures with high doses of G-CSF. The effects of hydrocortisone (HC) were also examined in these experiments. Like modulation by FCS, modulation of clonal growth by HC depended on the CSF used as stimulus, having no effect in cultures with G-CSF, inhibitory effects with CSF-1, and variable effects with GM-CSF related to CSF concentration.     

Lack of correlation between two markers of lymphocyte differentiation: 5' nucleotidase activity and T lymphocyte colony formation

Ecto 5' nucleotidase (5' NT) activity and T lymphocyte colony formation (TLCF) are both reputed to be markers for lymphocyte maturation. In order to determine whether these two expressions of lymphocyte activity are related, we compared 5' NT activity with the TLC forming capacity of mononuclear cells from three study groups: normal adults, cord blood, and patients with immunodeficiencies. Despite individual examples of correlation between these two measurements, there was poor overall correlation in any of the groups studied. Although both measurements may reflect maturation of certain cellular activities, these are unlikely to be related.     

Cell-cell cooperation in lymphocyte colony formation: studies in human allogeneic marrow transplantation

The pace of restoration of phytohemagglutinin- (PHA) stimulated lymphocyte colony-forming response was investigated in 50 bone marrow transplant (BMT) recipients (49 allogeneic, 1 syngeneic) studied on 86 occasions. On the majority of occasions (28 of 48), patients studied early (3 to 8 wk) after BMT failed to make detectable lymphocyte colonies, whereas patients studied late (greater than 6 mo) after BMT displayed responses comparable to those of healthy adult volunteers. The sequential study of 10 of the 15 patients with positive lymphocyte colony-forming responses early after BMT revealed that this response is short-lived. The results of recipient donor mixing experiments and experiments involving the addition of the lymphokine interleukin 2 (IL 2) to recipient cells indicated that lymphocytes obtained from unresponsive recipients evaluated early after BMT can be driven to colony formation, and suggest that the major limiting component in such subjects is functional T help.     

The formation of stable E-rosettes by human T lymphocytes activated in mixed lymphocyte reactions.

The aim of the present study was to determine whether activation of human T-lymphocytes affects their interaction with sheep red blood cells (SRBC). Less than 3% of the E-rosettes formed by freshly isolated peripheral blood lymphocytes (PBL) and SRBC are stable and do not disintegrate after incubation at 37 degrees C. In contrast, about 30% of PBL kept in culture for 5 days in the presence of mitomycin C-treated allogeneic lymphocytes were found to form stable E-rosettes. Whereas no rosettes were formed by freshly isolated PBL incubated with human red blood cells at 24 degrees C, 15% of the cells recovered from mixed lymphocyte reactions (MLR) formed such rosettes. When responder PBL were maintained in culture in the absence of allogeneic stimuli the proportion of cells forming stable E-rosettes depended on the serum present in the medium. Less than 5% of the responder cells kept in medium containing human serum or in serum-free medium formed stable E-rosettes, whereas 18% of the cells maintained in medium containing fetal calf serum formed stable E-rosettes. The proportion of cells forming stable E-rosettes increased before any increase in DNA synthesis was detectable in MLR. Indeed, a high proportion of cells forming stable E-rosettes appeared in MLR taking place in serum-free medium, without any accompanying increase of DNA synthesis. Depletion of cells forming EAC'-rosettes from responder PBL increased the proportion of cells forming stable E-rosettes in MLR. Exposure of the cells recovered in MLR to specific anti-T sera inhibited the formation of both stable and regular E-rosettes. Exposure of the cells recovered in MLR to anti-Ig serum had no effect on the formation of regular rosettes. Anti-Ig serum strongly inhibited the formation of stable E-rosettes by cells grown in medium containing human serum, but had no effect on the formation of stable E-rossettes by cells grown in either serum-free medium or in serum containing fetal calf serum. It is concluded that activated human T lymphocytes are characterized by their capacity to form stable E-rosettes, resistant to incubation at 37 degrees C, and by their capacity to acquire an immunoglobulin coat, possibly by binding immunoglobulin molecules present in their environment.     

B and T lymphocyte colony formation in agar: 2-mercaptoethanol-activated albumin can substitute for 2-mercaptoethanol.

The effect of 2-mercaptoethanol (2-ME) activated albumin (MaSF) on mouse B lymphocyte colony (BLC) formation and on human phytohemagglutinin (PHA)-induced T lymphocyte colony formation (TLC) formation in semisolid agar medium was studied. MaSF was found to stimulate colony formation comparable to the stimulation obtained with 2-ME. MaSF could not substitute for serum in any of the agar culture systems. BLC formation stimulated by MaSF was obtained with spleen cells from athymic nude mice and nonadherent spleen and lymph node cells of normal mice suggesting a direct effect of MaSF on the colony-forming B cell without interference with T cells or macrophages. The results suggest that the stimulatory effect of 2-ME in the BLC and TLC agar systems is mediated by 2-ME-activated albumin present in the culture medium.     

Differential effect of cyclosporin A on the expression of T and B lymphocyte activation antigens

We have used a monoclonal antibody (Mab) to the interleukin 2 (IL 2) receptor as well as a Mab to the transferrin receptor to analyze the effects of cyclosporin A (CsA) on the induction and expression of these activation antigens on mitogen-stimulated murine T and B lymphocytes. The same concentration (0.25 microgram/ml) of CsA that produced optimal inhibition of the T cell proliferative response to concanavalin A (Con A) was also very effective at inhibiting IL 2 production and the induction of IL 2 responsiveness, as well as the expression of the IL 2 and transferrin receptors when measured 72 hr after mitogen activation. Surprisingly, CsA only minimally inhibited expression of these receptors 24 hr after the addition of mitogen; however, T cell blasts recovered from these cultures failed to respond to IL 2 even though IL 2 receptor expression was only modestly decreased. These results suggest that inhibition of the maturation of receptor expression is secondary to an early effect of CsA in blocking the induction of IL 2 responsiveness or to an arrest in the sequence of events required for maturation of T cells that bear high densities of these receptors. In contrast to the results observed with T lymphocytes, CsA had no effect on the B cell proliferative response to lipopolysaccharide (LPS) or on the induction of the IL 2 and transferrin receptors on activated B lymphocytes.     

Characterization of human megakaryocytic colony formation in human plasma

We have analysed the contribution to megakaryocyte colony formation in methylcellulose made by human plasma, serum, media conditioned by phytohemagglutinin (PHA) stimulated leukocytes (PHA-LCM), erythropoietin (EPO) preparations, and platelets. The culture system was used as a bioassay for megakaryocyte colony stimulating activity (Meg-CSA) in plasma samples of patients with perturbed megakaryocytopoiesis. Preparations of heparinized platelet-poor plasma yielded the most consistent results. Platelet-poor plasma of normal subjects will at best facilitate the occasional growth of small megakaryocyte colonies. Colony frequency and size are reproducibly enhanced in the presence of PHA-LCM as a source of exogenous Meg-CSA. Commercially available EPO preparations may vary in their content of activities that influence megakaryocyte colony formation. Addition of these preparations to cultures that contain plasma and PHA-LCM usually does not enhance colony formation. In contrast to platelet-poor plasma, platelet rich plasma and serum are less supportive of megakaryocyte colony growth. It is suggested that this loss of activity may be related to the release of inhibitors by activated platelets or alternatively caused by absorption of activities by platelets. Plasma samples from patients with megakaryocytopoietic dysfunction may contain components that promote colony formation without addition of PHA-LCM or EPO. This phenomenon is consistently observed for patients with severe aplastic anemia and bone marrow transplant recipients after completion of their ablative preparative regimen.     

Effects of recombinant human interferon alpha on human megakaryocyte and fibroblast colony formation

Effects of recombinant human interferon alpha (HuIFN-alpha) on human megakaryocyte (CFU-MK) and fibroblast (CFU-F) colony-forming cell growth were studied. Concentration-dependent inhibition of both CFU-MK and CFU-F by HuIFN-alpha was demonstrated. Statistically significant suppression of both CFU-MK and CFU-F was seen at a HuIFN-alpha concentration of 1000 U/ml or greater. No significant difference was found between HuIFN-alpha treated cultures and controls for the distribution of CFU-MK types and for the size and cell morphology of CFU-F. When a concentration of 1000 u/ml HuIFN-alpha was added at varying time points during the marrow cultures, decreased numbers of megakaryocyte and fibroblast colonies only appeared at the early days of cultures. When bone marrow cells were incubated with HuIFN-alpha for different periods of time prior to initiation of cultures, a reduction of megakaryocyte colony formation also occurred. These studies demonstrate a suppressive effect of HuIFN-alpha on human CFU-MK and CFU-F growth. This effect seems to occur at the initial stages of CFU-MK and CFU-F development.     

Direct and indirect effects of recombinant human granulocyte-colony stimulating factor on in vitro colony formation of human bladder cancer cells

Although the present experimental use of recombinant human granulocyte-colony-stimulating factor (rG-CSF) has been proven to alleviate the myelosuppression induced by antitumor chemotherapy, it is also believed to stimulate growth of some nonhematopoietic tumor cells. We investigated both the direct and indirect effects of rG-CSF on in vitro colony formation of human bladder cancer cell lines using a modified human tumor clonogenic assay. Peripheral blood mononuclear cells (PBMC) were used as feeder cells (a mixture of 5×10⁴ monocytes/dish and 5×10⁵ lymphocytes/dish obtained from healthy donors). Human bladder cancer cell lines KK-47, TCCSUP and T24, all derived from human transitional-cell carcinomas, were incubated continuously with various concentrations of rG-CSF ranging from 0.01 ng/ml to 10 ng/ml both with and without PBMC for 7–21 days. The concentrations of rG-CSF used were chosen as being in the range of achievable serum concentrations in patients treated with rG-CSF. At the end of incubation, colonies were counted under an inverted phase-contrast microscope, and an increase in the number of colonies in comparison with the control was used to evaluate the effects of rG-CSF. Results were expressed as a percentage of controls. rG-CSF in the upper layer at concentrations ranging from 0.1 ng/ml to 10 ng/ml stimulated the colony formation of all the cancer cell lines tested in the absence of PBMC in the feeder layer, whereas cells with PBMC in the feeder layer were significantly stimulated more than those without PBMC in the feeder layer (P<0.05) up to a certain concentration, which varied from cell line to cell line. At higher concentrations of rG-CSF, no further stimulation but, on the contrary, a decrease in colony formation was observed in cells with PBMC in the feeder layer in all the cell lines tested. Colony formation in KK-47 and T24 cell lines was significantly inhibited at 5 ng/ml and/or 10 ng/ml rG-CSF compared with cells without PBMC in the feeder layer. Our results suggest that rG-CSF may have both direct and indirect stimulatory effects on the growth of human bladder cancer cell lines in vitro. The results obtained also raise the possibility of adverse effects of rG-CSF in bladder cancer patients whose malignant cells may be directly and indirectly stimulated by this factor while it is being used clinically to alleviate the myelosuppression induced by antitumor chemotherapy.     

Influence of hydrocortisone on the survival and cluster and colony forming characteristics of normal human granulocyte-macrophage progenitors

Abstract. This study was performed to determine the colony and cluster forming ability of granulocyte-macrophage (CFU-GM) progenitors of normal human blood low density cells cultured in a liquid culture system in the presence and absence of physiological doses of hydrocortisone (He). The CFU-GM recovered from the liquid cultures were assayed in soft agar medium. The results of the assays indicated that time-related development of clusters and colonies over 1-16 days, proliferative responsiveness to a source of colony stimulating activity, number of cells developed per colony, and the cellular composition of clusters and colonies produced from CFU-GM recovered from 14-day-old liquid cultures with 1·0 µM. He, were all similar to those that developed from the normal human blood low density cells. However, a higher fraction of the CFU-GM in day 14 liquid cultures with 1·0 µM He were in DNA synthesis phase compared with the CFU-GM from the peripheral blood. This study confirmed the results of previous studies showing lower numbers of recognizable neutrophilic granulocytes and improved survival/proliferation of CFU-GM at day 14 in liquid cultures with 1·0 µM He compared with cultures without He. The present results suggest that the normal human blood CFU-GM which persists and proliferates under the influence of He in a liquid culture system is similar in ontogeny to the blood CFU-GM, and that the recovery of CFU-GM from liquid cultures under the influence of He appears to be exerted through stimulation of proliferation and controlled differentiation.     

Influence of hydrocortisone on the survival and cluster and colony forming characteristics of normal human granulocyte-macrophage progenitors

This study was performed to determine the colony and cluster forming ability of granulocyte-macrophage (CFU-GM) progenitors of normal human blood low density cells cultured in a liquid culture system in the presence and absence of physiological doses of hydrocortisone (Hc). The CFU-GM recovered from the liquid cultures were assayed in soft agar medium. The results of the assays indicated that time-related development of clusters and colonies over 1-16 days, proliferative responsiveness to a source of colony stimulating activity, number of cells developed per colony, and the cellular composition of clusters and colonies produced from CFU-GM recovered from 14-day-old liquid cultures with 1.0 microM Hc, were all similar to those that developed from the normal human blood low density cells. However, a higher fraction of the CFU-GM in day 14 liquid cultures with 1.0 microM Hc were in DNA synthesis phase compared with the CFU-GM from the peripheral blood. This study confirmed the results of previous studies showing lower numbers of recognizable neutrophilic granulocytes and improved survival/proliferation of CFU-GM at day 14 in liquid cultures with 1.0 microM Hc compared with cultures without Hc. The present results suggest that the normal human blood CFU-GM which persists and proliferates under the influence of Hc in a liquid culture system is similar in ontogeny to the blood CFU-GM, and that the recovery of CFU-GM from liquid cultures under the influence of Hc appears to be exerted through stimulation of proliferation and controlled differentiation.     

The effect of hydrocortisone and cyclosporin A on bacillus Calmette-Guérin epitheloid cell granulomas

The injection of bacillus Calmette-Guérin (BCG) intradermally into the ear of guinea pigs leads to the formation in the draining lymph node of granulomas containing epithelioid cells with rough endoplasmic reticulum (RER) and an absence of phagocytosed material. BCG granulomas in hydrocortisone- or cyclosporin A (CsA)-treated animals contain mononuclear phagocytes with no RER. In CsA-treated animals, these cells contain fragments of phagocytosed organisms. CsA was given at two doses, 25 mg/kg orally and 50 mg/kg ip. The higher dose completely suppressed the delayed hypersensitivity (DH) response to purified protein derivative (PPD) but the lower dose did not affect the level of the DH response, but had a profound effect on epithelioid cell formation. The role of lymphokines in the maturation of the monocyte/macrophage to epithelioid cells is discussed.     

The effects of 1,25-dihydroxyvitamin D3 on human T lymphocyte activation and proliferation: a cell cycle analysis

Recent studies have demonstrated that 1,25-dihydroxyvitamin D3 (calcitriol), the most biologically active metabolite of vitamin D, is a potent inhibitor of both lectin- and antigen-driven human T lymphocyte proliferation. To better characterize this effect, we performed cell cycle analysis of both untreated and calcitriol-treated peripheral blood mononuclear cells after PHA stimulation. By using the metachromatic dye acridine orange and flow cytometry, we found that calcitriol blocks the transition from the early, low RNA compartment of G1 (G1A) to the late, higher RNA compartment of G1 (G1B). Consistent with this observation was the inability of exogenous IL 1 or phorbol myristic acetate to overcome calcitriol's suppression of DNA synthesis. Indomethacin slightly reversed calcitriol's inhibition of transition from early to late G1, suggesting a minor, prostaglandin-dependent component to calcitriol's antiproliferative activity. Finally, by using the monoclonal antibodies anti-Tac and OKT9, we found that calcitriol had no effect on IL 2 receptor expression, an early G1 event, but markedly inhibited transferrin receptor expression, an IL 2-dependent, late G1 event. Thus, analysis of calcitriol's effects on the expression of these T cell activation antigens provides further evidence of the cell cycle specificity of calcitriol's action in regulating human T lymphocyte proliferation.     

Properties and separation of T lymphocyte growth stimulatory activity (TL-GSA) and of granulocyte-macrophage colony stimulatory activity (GM-CSA) produced separately from two human T lymphocyte subpopulations.

We have previously identified two stimulatory activities affecting blood cell maturation in PHA-stimulated human lymphocytes conditioned medium (PHA-LyCM). One was granulocyte-macrophage colony stimulatory activity (GM-CSA), and the other was T lymphocyte growth stimulatory activity (TL-GSA) in suspension culture. In this paper we have shown that although both activities can be produced from purified non-adherent human T lymphocytes, they are produced from two distinct subpopulations. The production of these activities was greatly enhanced by T cell mitogens. Both protein factors were relatively heat stable (56 degrees, 30 minutes), were sensitive to trypsin treatment and were specific for primate blood cells. These two activities were fractionated by means of ammonium sulfate precipitation, Sephadex G-150 gel filtration, DEAE cellulose and Con A-Sepharose column chromatographies. MW of the major peak estimated from the elution volume of gel filtration in the presence of 0.5 M NaCl was 40,000 for GM-CSA and 13,000 for TL-GSA. Results from Con A-Sepharose column showed that while about 70% of TL-GSA was bound to Con A, less than 25% of GM-CSA was bound. These observations show that the majority of TL-GSA and GM-CSA were separable by these two conventional column chromatographic methods.